Glass



Patented 23, 1929.

awn-ED STATES PATENT/OFFICE Io Drawing.

. character, but i WILLIAM C. TAYLOR, OF COBNIN'G, NEW YORK, ASSIGNOB TO CORNING GLASS WORKS, OF COMING, NEW YORK, A CORPORATION OF NEW YORK.

ena'ss.

I'have discovered that the salts of molybdenum and also of tungsten whichtwo ele- 95 and 185)'may, in spite of their high cost,

be used with advantage in the production of opal glasses; that when so used in relatively small quantities they give, in a glass otherwise suitable, and melted under proper condi- 'tions, a dense opal, and that the opacity produced thereby is not subjected to beingburnt the present opals.

Generally speaking, glasses suitable to be opalized by the named elements are glasses which are sufficiently acidic'in character and are melted under oxidizing conditions.

, In other words glasses which are melted under oxidizing conditions will produce opacity provided the. .are suiiiciently acidic in they are not sufliciently acidic in character theywill be practically clear and colorless. On the contrary glasses out on overheating as is the case in many of which are melted under non-oxidizing condi-' tions do not produce opacity but tend to produce color regardless of whether they are acidic or basic. I

It is well known'in the art that acidity in a glass is not strictly comparable to acidlty in the ordinary use of the term, because in the latter sense there is no known means of determining when a glass ceases to be acidic and becomes' basic or vice versa.

The acidity of a proper glass may be due to a variety of causes, for instance, to the introduction into an otherwise alkali batch of a substantial quantity of boric oxide, or to the use in the batch of known non alkali-earth bases (such as lead) in lieu of the alkali-earth 'bases (such as lime) commonl em 10 ed, or

to decreasing the amount of t e a all (such as soda present. Thepresence of the alkali-' sary'to produce opacity may be brought about by the addition to the batch of an oxidizing 4 agent such asniter.

As examples of glasses embodying this in- 4 vention, the following table of four glasses Application filed July 21,1928. Serial No. 124,101.

own metallic is given in terms of percentage glass composi- I ,tion as calculated from the respective batches.

A I B o l D 71. 72. as. I

16:25 17.00- 11.60- a 4-2" A110; 13:5, M00; 2.00 1.00 .40

In the above table glass A is a lead boro silicate, glasses B and G are calcium boro-y.

silicates, and glass D is a lead flint, all of them carrying, in-addition to the usual ingredients of such glasses, a salt of a known metallic element of the sixth group above stated to be effective to produce opacity.

Glasses B and 0, due to the presence of l fluorine and aluminum oxide, have a tendency toward. 9Pacity,,so that a relatively small amount of the sixth group element is used.

The presence of the small amount, however,

permits the reduction of the amount of fluorine otherwise necessary to produceopacity in such a batch and'thcreby increases the life of the refractories and reduces danger of clearing on rolonging heating. ()paclty can be obtaine with these glasses without fluorine by increasing the sixth group element oxide. v

Glass A has high thermal endurance and is a type of glass with which it has heretofore been difiicult to obtain opacity 1 ,In the above boros'ilicate asses, 'A, B and C, tun sten trioxide (W0 may be substituted or molybdenum trioxide (M00,) in the direct ratio of their respective molecular weights (i. e., 'in the ratio of 1.6 parts of WO, for 1 part of Mo(),), without departing from my invention and without essentially changing the characteristics of the resultant glass. In the case of the lead flint glass, D, the substitution of WO, for M00, is not as desirable because the opalescence resulting therefrom is not of sufficient density to be of commercial use.

In carrying out my invention a proper batch is mixed of ingredients necessary to. give'the desired composition, this batch including a small quantlty of the properpxidlzing agent such as sodium nitrate, and is-melted, the presence of the sodium mtrate causing the melting to be under oxidizing conditions:

The term opal is here used to. designate lasaes which are more or less opaque, and

includes lasses which are opa no as well as those w ich are nearly op escent. The specified group elements, however, tend "to produce dense op Having thus escribed my invention, what I claim and desire to secureby Letters Patent of the United States is 1. The hereinbefore described method of obtaining an opal glass which consists in melting under oxidizing conditions an acidic batch containing a known metallic element, of the even series of the sixth periodic group ha an atomic weight between 95 and 185.

2. he hereinbefore described method of obtaining an opal glass which, consists in melting under oxidizin conditions a batch containing a substantia percentage of boric oxideand a known metallic element of the even series of the sixth periodic group havin an atomic weightbetween 95 and 185.

i Theh'ereinbefore describedmethod of obtaining an opaltglass which consists in meltin under oxidizin conditions a lead flint containing aown metallic element of the even series of the sixth periodic grou having an atomic weight between 95 and 85. v

'4. A batch for an opal glass, said batch acidic in character and containing an oxidizing agent and a salt of a known metalbetween 95 an signature.

lic element of the even series of the sixth periodic group having anatomic weight between 95 and 185.

5. A batch for an opal glass containing a substantial quantity of boric oxide, an oxidizing agent, and a salt of a known metallic element of the evenseries of the sixth riodic group having an atomic weight bgtween 95 and 185.-

6. A batch for an opal lead flint glass containing an oxidizing agent and a-salt of a known metallic element of the even series of the sixthperiodic group having an atomic weight between 95 and 185.

7. An acidic 0 a1 glass containing a salt of a known metal ic element of the even series of the sixth periodic up havin an atomic weight between an. 185, melte under oxidizing conditions.

8. An opal glass containing a substantial quantity of boric oxide and a salt of a known metallic element of the even series of the sixth periodic group having an atomic weight 185, melted under oxidizing conditions.

9. An opal lead flint glass containing a salt of a known metallic element of the even series of the sixth periodic group havin an atomic weight between 95 and 185, mel under oxidizing conditions. i

. In testimony whereof I hereunto aflix my c. TAYLOR. 

